Adjustable spirit level



Ap 1947; E. A. KELLEk 2,419,451

- J ADJUSTABLE SPIRIT LEVEL 7 Filed Oct. 5, 1944 2 sneaks-sheet 1 INVENTOR warrifiizllez' I E. A. KELLER ADJUSTABLE SPIRIT LEVEL' April 22, 1947.

Filed Oct. 5, 1944 2 Sheets-Sheet 2 jaiuj rd a.

Patented Apr 22, 1941 2,419,451 ADJUSTABLE sPrRrr LEVEL Edward A. Keller, Aurora, 111. Application October 5, 1944, serialivo. 557,254 7 Claims. (01. 33-208) This invention relates to adjustable or expansible devices. More particularly it relates to lan expansible spirit level.

, Adjustable or. expansible spirit levels as well 'as ot e adjustableior expansible devices are well 'known in the art. The adjustable or expansible spiritv vlevels heretofore known, however, have beenrsubject to several disadvantages. Among ,these an outstanding one is that when drawn out .or expanded beyond their minimum length the straight onflatedges are not continuous so that }while scrvingltonindicate whether a particular line .or surface isi 'horizontal or vertical they are :not suitable tq'indicate' at'the same'time that the surfaceis planeor thatthe line isi'periectly straight. Thus when applied to a timber, for examplegthey will'indicate whether the two points lragainst rvhich their ends rest are vertically or m mmary aligned, but will not .show. whether lbiihotfthe intermediate points lie on astraight Jineconnecting} the two end points ,since they do not in their. expanded state provide a convtinuous straight edge. ,In like manner when emfploye dby aplasterer, for example, they will in- :dicate whether two points ona corner are ver- L.tically oneabove the other but will not indicate whether theintermediate points are in line, with these two, so that the corner is perfectly straight andvertical, jI V 'j Also such spiritvlevelsand other expansible del yices havaalsoc sufiered from the disadvantage that when Qpr'ovided with expansible means on leitherfiend' oreither side it is diflicult to draw these. expansible means out to equal distances so that'. jthe,'device such asnthe spiritlevel remains sjymr'nietricall. about the. midpoint, Iniview of these'j disadvantages, expansibledevices, .particularlyexpansiblespirit'levels, have not enjoyed :the commercial success which they might have otherwise 'and havevnot satisfied the demand for satisfactory xpansible devices, particularly expansiblespiritlevlsf I It is therefore an object of this 'inVentiOn to provide an expansible device having a continuouscstraight edge substantially throughout its lengthandin anypositionjtowhich it is expanded orcontracted. [1A more specific object is to provide an expansible spirit level having a continuous straight ed Substantially throughout its length and in zany position to which it is expanded or .con- .tracted. if V A 'still j rurther object is to provide an ex- ,pansible spiritlevel whichmay be drawn out or j panded n bcthends and which in any posiure 1;

tion to which itis expanded or contracted has in the plane of the spirit bubble tube a continuous straight edge substantially throughout its t V I. lit: Still another object-is to provide a'n'e'xpansion device adapted to be expanded in opposite directions and whichwhen so expanded remains substantially symmetrical aboutits midpoint in completely contracted position;-

ff 1; A still more specific object is to provide-'anexpansible spirit level adapted to be expanded on both ends and whichwhen-so expanded remains substantially symmetrical aboutit oint in completely contracted position? Another, object is to provide arr expansilile spirit level adapted to be expanded on both'ends which when so expanded remains substantially symmetrical about its midpoint" injconipletely contracted position and which in any po'sitionto which it is adjustable :-provides a gcontinuous Tstraight edge substantially th'r'pughbut its len gth.

Other objects will be apparent-hereinafter.

In order thatfthe invention may' be 'better.

understood reference is made vtc'theja'ccg m'dpanying drawing forming a part of thisspecification which indicates how the foregoing pbjectsniay be accomplished and in whicrfj-i Figure 1 is a View in persp cti off nd:- pansible spirit level embodying featillesf offthe present invention, 'showingthe 'devi'c "in'completely expanded position; A N {f Figure 2 is' an exploded 'view in; perspective showing the variousparts which formhe spirit level illustrated in Figure 1;] Figure 3 is a section on'th Figure 4 is aview oif one edgeith shown in Figural: f j

Figure 5 is a view ixreleva o of the shown in Figure'l; v M Figure 6 is a section onthe the body l2 and cooperating tonguesfiflon members M and I 6. The cooperating,tongues fl and usual bubbletubes 26 which are mounted in-openlugs 28 formed centrally in the boxes. In constructing the level I suitable supporting material such as plaster of Paris is positioned in the open! in s 28 and the bubble tubes 26 are then mounted in the plaster of Paris support. Cover plates 30 are provided to close the ends of openings 28. These are secured in any suitable manner, as, for example, by means of bolts or screws 32. An opening 34 extending between the opposite faces ,;:oi e ach;box-24 is provided so that the bubble -tubes may beseen. Means including an opening ,3 6 is also provided in body portion l2 for mounting a pair of bubble tubes 26 centrally therein. In "the;manner above described, suitable mounting m ateri al such as plaster of Paris is positioned in .the opening ;36 and the. bubble tubes 26 are .mounted therein in position as shown in Figure 5. Opening 38 extending through the central portion of body; ]2 permits .=the central bubble tubes 26 to beyiewed from either face of the level In. v It apparent that these two central bubble -tubes;26 .;being positioned asindicated in Figure are read when the level isextended in horizontal the fact that the threads 60 and 62 are equally pitched the members 14 and IE will necessarily move in or out the same distances.

Although means may be provided for turning the rod 50 by hand such operation of the level It) shown in the drawings herein is not contemplated. Instead the threads 50 and 62 are given a substantial pitch on the order of 45 whereby the rod 50 is caused to turn by forcing the: ends l4 and H3, or both, inwardly or outwardly with respect to the body [2. It will further be apparent that by reason of the fact that the ends 14 and I6 are both threadingly mounted on the rod 50 it is possible to expand the level or contract it by .positionand .thatfthe bubble tubes 26 in boxes 24,

Ibeing positionediat right angles to those in the .centeras is also: shown in Figure 5, are read when .the :level ,is extended vertically. 1; To keep the level symmetrical about the central bllbbles lfl-i inlanyfposition to which it may be l adiusted lllgs, ll provided with threaded openings 42 are;- screwed or bolted on the inner ends of frames 22. by screws or bolts 44, for example. jlfhe se lugs '40 reciprocate in generally rectangular openings 46 provided in the :body I 2. As is appar- I ent th e Figure 1, the frame members 22 carrying lugs extend inbeyond the adjacent opening 48 center pertign oi body I 2 so that lugs 40 are positioned. in .the opening 46 remote from the extension T4 or lB-ofWhich they form a part. In a this connection it is also pointed out that a lon narrow opening 48 is provided in each frame 22 to permit the central bubble tubes 26 to be seen when frames 22 are in position since these frames would -otherwiseobscurethesejbubbles 28. The lugs 40 in the openings 46 are threadingly received on the opposite ends. of a threaded rod 50 extending through openings 52 provided centrally in the ends .5 1 of body l2 and through an opening 56 extending centrally and longitudinally through the eentral portionv58of body l2 which carries the central bubble tubes 26. The rod 50 is loosely wreceived in openings. 52 and 56 to permit it to "rotate thereinfor a. purpose, which will herein- .after beeome more apparent. The threads 60 and :pieces l4 and [Swill both be moved out or both 'be moved in at the same time and by reason of caps 66 to turn freely thereimfj in fact might better be referred to as helical grooves than as threads. In any event'j'such variations are within the scope of the invention. Also, instead of providing a threadwithin,the lugs 40 other means engaging in: the "helical grooves or threads 60 and 62, such astaj small pin, may be employed. r j' To secure the rod 50 against longitudinal movement circular depressions 64 are formedin the ends 54 of body l2 about the openings 52 to receive washers or caps 66. These washers or caps 66 are bolted to the ends of rod 50 by bolts 68. The washers or caps 6 6 turn with therodjll and accordingly the depressions?; are;made large enough anddeep enough to pe To provide a continuous straight edge ing substantially the full length'oi' the leg lly. sets of three wedge members 70, '12 an dj]4 ar,e

provided on each edge of the level l0, members 10 and vI l, as shown, are 'pref erably secured to or formed integral with the ends l4 and [6 respectively. 'I he'central wedge member 12 which cooperates with'the'endmembersflll and I4 is slidably mountedon thejcooperating members Ill and 14 by means of tongues IBjand [8 on member 12 and cooperating grooves 89 and 82 ,formed respectively on wedges' 'llliand'iffl.

The tongue and groove connection between wedg e members l0, l2 and I4 permitswedgfes llljand H to move longitudinally with respect to. wedge 72 and at the same time moves wedge 12 laterally to retain it in contact with members 10 and 14. In this manner a continuous straight edge; e 1 "L d ing the fulllength of the level] III is cqntinuousl'y maintained on each edge of ,level' Ill jalongfsurjfaces (Figures '1 and 4) lying"betweenbrql en ,line 84 and broken line .86.. lt wlll'belunderstood of course that theselines 84 and 86Ishift later- ,ally with respect to the level .jlll as jthelleyel .is expanded and contracted, their p'ositio i an time being determined respectivelyib ,88and 90 and corners 92 andflol wedges)", l2 and 14 (Figure 2). 1,, l1, .1; r As shown in the drawings the sets 0m l2 and 14 are oppositely positionedon' the two edges of the level I 0, that is, thewedge .1211) .one

edge is adjacent one face and thfwedge'ltfjoh the other edge is adjacentthe oppositeljace. Obviously, of course, both wedges 12 maybe ad- .iacent thesame face if desired. Similarly; the

central wedge member 12 may, for exampleibe 16, 18;80 and 82, or it may be fixed thereonand the end wedges 10 and M maybe'slidably mouritedfonthe'extensions l tandlli, the slidable wedge or'wedgesin both cases preferably beingresil- 'intly urged-into-contact with thebooperating wedge or wedgesor connected by means-such as tfln llesandgrooves'asshown.

g j I lilloewise, a variety of other modifications may be made in the structure, as will be apparent to those skilled'in the art, without departing from thaspifitand scope 'of the invention. Thus, by way-of illustration, various parts, such as the ends Id and [6, are shown as integral members, whereas if des'ired the elements of these parts may be {formed separately 'and'suitably secured together. Also, "the tongue and groove construction by which the various parts are slid'ably'engaged with each other may be replaced with-other equivalent means It will be apparent, however, that since thelevel i is a precision instrument. or at least is preferably constructed to be, it is desirable that the parts he engaged in such manner as to ensure that-they will be at-all times retained in their proper relationship to each other.

The various parts of the level 10 may be constructed iro'm'a variety of dilferent materials. Where a. high degree of precision is desired, some relatively strong, long-wearing material, such as a light metal, a plastic, ora hard wood will be indicated. ,It'is withinthe scope of the invention, however; to construct the level of any 'desired material.

' JIZhl-i advantages or thls'level'are apparent from thefloregding description. Rod 50 and cooperating glugs '40 serving to retain theiends l4 and H5 at all' times" at equal" distances from the 'center of body l2 have the advantage of keeping the level H] symmetrical at all times about the central bubble tubes 26 which is an important feature of the level. This is moreover accomplished automatically and without requiring any special attention on the part of the user. A further outstanding advantage of the level is that by reason of the cooperating wedge members a continuous straight edge is maintained on each edge of the level at all positions to which it is adjustable. Thus it is possible, whether the level is extended or contracted, to determine readily whether a given line or surface lying between the ends of the level is either perfectly vertical or perfectly horizontal throughout its length. The level disclosed herein thus possesses the advantages and properties of levels which are not extensible and at the same time may be extended or contracted depending upon whether the use to which it is put requires a long or short level. This is accomplished, moreover, without any substantial variation in the accuracy of the level due to the fact that it is at all times symmetrical about the center bubbles and due to the further fact that the bubbles which are used when the level is held vertically are at all times located substantially at the extreme ends of the level.

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A spirit level comprising a body carrying a spirit bubble tube and an expansible device comprising in combination means permitting expansion and contraction thereof and means for maintaining in the plane of said spirit bubble tube at least one continuous straight edge thereon during expansion and contraction extending substantially the full length of the device including at 6 least two cooperating wedge members, said means permitting expansion including portionsof'said device movable with respect to each other, one of which carries one of said wedge members and the other of which'carries anothen at least' pne of said wedgemembers also being supported for shifting to maintain engagement with said other wedge member during expansion and contraction.

2. An expansible spirit le elcomp'rising com bination means permitting expansion andcontraction thereof and means for maint'aining at least one continuous straight edge thereon during expansion and contraction extending substantially the full length of the spiritlevel including at least two cooperating wedge members, said means permitting expansionincluding portions of said spirit level movable with respect to each other, one of which carries one of said-wedge members and the other of which carries another, at least one of said wedge members-also being supported for shifting to maintainengagement continuously with said other wedge 'mem her during expansion and contraction. l f

3. An expansible spirit level comprising means for expanding and contracting the same longitudinally including a pair of extensions slidably mounted upon the opposite ends of a central member carrying a bubble tube, and means for main taining in the plane of the bubble tube a continuous straight edge on said level extending substantially the full length of said level at all positions to which said extensions are adjustable coinprising a pair of wedge members mounted respectively on said extensions and a third'wedg'e member supported intermediate said pair of wedge members and cooperating with said pair of wedge members, at least one of said three wedge members being shiftably mounted to permit shiftingthereof during expansion and contraction and said wedge members having means associated therewith for maintaining said wedge members in cooperative relation during expansion and contraction.

4. ,An expansible spirit level comprising means for expanding and contracting the same longitudinally including a pair of extensions slidably mounted upon the opposite ends of a central member carrying a bubble tube, and means for maintaining in the plane of the bubble tube a continuous straight edge on said level extending substantially the full length of said level at all positions to which said extensions are adjustable comprising a pair of wedge members mounted respectively on said extensions and a third wedge member supported intermediate said pair of wedge members and cooperating with said pair of wedge members, said pair of wedge members being rigidly mounted on said extensions and said third wedge member being slidably secured along its edge surfaces to the edge surfaces of said end wedge members.

5. An adjustable spirit level comprising means for expanding and contracting the same longitudinally including a pair of extensions slidably mounted on the opposite ends of a central member, a bubble tube mounted on said central member, means for maintaining in the plane of said bubble tube a continuous straight edge on said level extending substantially the full length of said level at all positions to which said extensions are adjustable, and means for causing said expansion and contraction to be uniform with respect to the longitudinal center of said central member, said means for maintaining the continuous straight edge including a pair of wedge members a: 7 mounted respectivel on said extensions and a third'wedge member supported intermediate said .pair of wedge members and cooperating with said pair of wedge members, at least one of said wedge members being shiftably mounted to permit shifting thereof during expansion and contraction and said wedge members having means associated therewith for maintaining said wedge members in cooperative relation during expansion and contraction and said means for causin said expansion and contraction -to;-be uniform including ;means held against longitudinal movement with respect to the center of said central member, having right and left hand threads on opposite ends thereof and threadingly engaging on its oppo- -side ends said pair of extensions. 6. An adjustable spirit level comprising means for expanding and contracting the same longitu .dinally including a pair of extensions slidably mounted on the opposite ends of a central member, a spirit bubbletube mounted on said central member, means for maintaining inthe plane of said bubble tube a continuous straight edge on ,said level extending substantially the full length .of saidlevel at all-positions .to which said extensions are adjustable and means for causing said expansion andcontraction to be Uniform with respect to the longitudinal center of said central member, ,said means for maintaining. the continuous straight edge-including a pair of wedge members mounted respectively on said extensions ,and a third-wedgemember. supported intermediate said pair of wedge members and cooperating pair of .wedge members, said pair of 1 groove connections. 4 l.

rwedge members being rigidly mounted onsaid 7 extensions and said third wedge member being slidably secured along its edge surfaces tozthe edge surfaces of said ;end members, and. said means for causing said expansion and contraction to be uniform including means held against longitudinal movementwith respect to the: center .of

said central member, having right and left hand threads on opposite ends thereof and threadingly engaging on its opposite-ends said pair or extensions, a e. v I

. 7. An expansible spirit level as described .in claim 6 further characterized in.that the. two wedge members are slidably secured to the third wedge member and the two extensionsare slidably' secured to the central member by tongue an -t-" Fl en ti I ltEFE The following references are -of record in he file of this patent; r:

' UNITED STATES PATENTS 

